US jet-chopper crash: Conflicting data shows 100-foot difference in altitude readings
Investigators continue to determine the cause of the midair collision between an American Airlines jet and a US Army Black Hawk helicopter near Washington, DC, which claimed 67 lives. Preliminary data show discrepancies in altitude reports, raising questions about airspace restrictions and flight procedures. A full investigation could take a year.
Investigators continue to determine the cause of the midair collision between an American Airlines jet and a US Army Black Hawk helicopter near Washington, DC, which claimed 67 lives. Preliminary data show discrepancies in altitude reports, raising questions about airspace restrictions and flight procedures. A full investigation could take a year. 
